In my professional opinion, go to a professional hair salon. If your hair is already not in good condition then it will need expert advice and TLC. You hair is fragile and when the condition is week then the colouring process and desired result can be difficult to achieve. The tone and depth of colour you would like is not as easy as one would think to get an even colour result. ...More >
I would recommend getting a consultation from your stylist and seeking their professional advice on which colour treatment is the best for your hair.
Permanent, semi permanent or temporary colour may all be possible but the condition of your hair is the overriding factor.
You are correct to be concerned over a flat colour result. This can happen when hair is damaged and you may need to have tonal pigment put into your hair first, to ensure your colour result tonal refection is true.
When I use to have my own salons I had many clients come to see me in despair, after home hair colour experiments. As professional hairdressers we spend years of educational learning to be able to confidently select and predict a colour result believe me it is not easy.
So please for your own sake ensure your hair receives what it deserves.
Visit the salon and your stylist!